Aim:
The velocity associated with the maximum aerobic power (vVO2max) is an important parameter for both laboratory testing and training on the field. However, the modality of the test utilised to obtain vVO2max might be crucial. Indeed, the slope of the increase in velocity during treadmill incremental ramp test does not always match the rate of the cardiorespiratory and metabolic adjustments to exercise. The aim of the present study was to compare two different types of testing protocols (ramp vs square wave) for vVO2max assessment. Hypothesis can be made that during the ramp test, due to the fast increase in work rate compared to cardiorespiratory and metabolic adjustments, vVO2max could be overestimated.
Method:
Eight physically active males (age: 22.3±1.5 years, stature: 175.3±4.2 cm, body mass: 71.1±5.2 kg; mean±SD) reported to the laboratory twice, with at least 48 h recovery in between, to perform two maximum incremental tests (in random order) on a motorised treadmill for VO2max and vVO2max assessment. During the first visit (T1) a ramp protocol (1 km/h per min) was performed until volitional exhaustion, while during the second visit (T2) a square-wave incremental protocol (six work loads of 4 min each, with 5 min of rest in between) was utilized. During tests, oxygen uptake (VO2), CO2 production (VCO2), expiratory ventilation (VE) were determined on a breath by breath basis. Heart rate (HR) was measured by a portable HR monitor. Blood lactate concentration [La-] was measured at rest (baseline) and at peak exercise. Statistical differences were assessed by one-way analysis of variance for repeated measures.
Results:
At maximal exercise, vVO2max was significantly higher in T1 (18.7±1.7 km/h) compared to T2 (16.7±1.5 km/h). No significant differences were found between T1 and T2 for VO2 (3921.2±462.1 vs 4004.5±459.6 ml/min for T1 and T2, respectively), VCO2 (4318.6±553.6 vs 4338.3±603 ml/min for T1 and T2, respectively), VE (161.1±8.9 vs 159.5±15.8 l/min for T1 and T2, respectively), [La-] (10.45±1.52 vs 13.1±1.52 mM for T1 and T2, respectively), and HR (182.4±4.2 vs 180.6±4.1 b/min for T1 and T2, respectively).
Conclusion:
Despite similar VO2max values, vVO2max was overestimated during ramp test (T1) compared to the square-wave test. This protocol-induced difference must be taken into account when planning relative submaximal workloads for training purposes.
References:
-Midgley A.W.,McNaughton L.R., Carroll S. Time at VO2max during intermittent treadmill running: test protocol dependent or methodological artefact? Int J Sports Med 2007; 28: 934–939.
-Harling S.A.,Tong R.J., and Mickleborough T.D. The oxygen uptake response running to exhaustion at peak treadmill speed. Med. Sci. Sports Exerc., Vol.35, No.4, pp.663–668, 2003.